title: Dysregulation of upstream and downstream transforming growth factor-β transcripts in livers of children with biliary atresia and fibrogenic gene signatures.
abstract: BACKGROUND
  Our previous work demonstrated that the transforming-growth factor (TGF) β pathway plays a central role in the liver fibrosis associated with experimental biliary atresia (BA). To confirm these findings in humans, we performed an in silico analysis of publicly available microarray data from liver specimens from children with BA, with the hypothesis that the TGF-β pathway would be dysregulated.
  
  
  METHODS
  We analyzed publicly available liver gene expression microarray data from 47 infants with BA. We re-analyzed the microarray image files and clinical data to compare gene expression differences between the fibrogenic and inflammatory cohorts identified in the initial study. Targets from the microarray analysis were confirmed using the animal model of BA.
  
  
  RESULTS
  Analysis of variance (ANOVA) detected 6903 transcripts (2822 distinct genes) differentially regulated between groups (p < 0.01; fold change >1.2). We used a targeted approach to identified a subgroup of 24 TGF-β-related transcripts. Expressions for procollagen transcripts were increased in the fibrogenic group (1.2-fold to 1.4-fold); expression of matrix metalloproteinase (MMP)-7 was similarly increased 2-fold, while MMP-9 and plasminogen activator inhibitor-1 were decreased 2-fold and 3-fold respectively. Integrins β5 (1.18-fold) and β8 (1.84-fold) also demonstrated increased expression in the fibrogenic group. Increased expression of β5 (3-fold) and β8 (5-fold) as well as Smad-3 (4-fold) and Smad interacting protein (SIP)-1 (3.5-fold) mRNA was confirmed in experimental BA. Phosphorylated Smad-3 protein in the experimental group was also nearly twice that of the control group, further implicating the TGF-β pathway.
  
  
  CONCLUSIONS
  Gene transcripts for known upstream and downstream TGF-β mediators are differentially expressed in liver specimens from children with BA and a fibrogenic gene signature. The same integrins that were dysregulated in the human specimens were also found to be up-regulated in our animal BA model, as were other intermediaries in the TGF-β pathway. Further investigation into whether these mediators may be attractive targets for future therapy in children with BA is warranted.
authors.affiliation: Sheihk Zayed Institute for Pediatric Surgical Innovation, Children's National Medical Center, Washington, DC 20010, USA.
authors.forename: Tatiana
authors.initials: T
authors.lastname: Iordanskaia
authors.forename: Monica J
authors.initials: MJ
authors.lastname: Hubal
authors.forename: Emily
authors.initials: E
authors.lastname: Koeck
authors.forename: Christopher
authors.initials: C
authors.lastname: Rossi
authors.forename: Kathleen
authors.initials: K
authors.lastname: Schwarz
authors.forename: Evan P
authors.initials: EP
authors.lastname: Nadler
mesh_terms: D000818:Animals; D001656:Biliary Atresia / Q000150:complications / Q000235:genetics* / Q000378:metabolism; D015415:Biomarkers / Q000378:metabolism; D015536:Down-Regulation; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D007150:Immunohistochemistry; D007223:Infant; D008099:Liver / Q000378:metabolism*; D008103:Liver Cirrhosis / Q000209:etiology* / Q000235:genetics / Q000378:metabolism; D008807:Mice, Inbred BALB C; D020411:Oligonucleotide Array Sequence Analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016212:Transforming Growth Factor beta / Q000235:genetics* / Q000378:metabolism; D015854:Up-Regulation
chemical_list: D015415:Biomarkers; D016212:Transforming Growth Factor beta
keywords: Biliary atresia; Liver fibrosis; TGF-beta